The purpose of this research is to document the effects of microwave radiation (MWR) on the nervous system by examining single unit discharge in those sensory systems that are responsive to continuous wave or pulse modulated MWR. Previous work in our laboratory confirmed that single units in the vestibular pathway and single units in the auditory pathway show an acute response to continuous wave and pulse MWR, respectively. The primary aims of the projects will be to derive a more complete quantitative understanding of these interactions, to investigate the underlying physical mechanisms, and to evaluate the general biological significance of these MWR effects in cats. Similar studies using laboratory primates will then follow. The response of single vestibular units and of single auditory units to appropriate physiological stimuli will be recorded via glass micropipette located in the eighth nerve and in brain stem vestibular and cochlear nuclei. Thus functionally identified, the subsequent response of the units of MWR (915 and 2450 MHz) applied to the head will be noted. For vestibular units, the emphasis will be on their response to physiological angular acceleration of the head as compared with their response to exposure to near field continuous wave MWR. For auditory unit the emphasis will be on their response to physiologic acoustic stimuli (tone bursts and clicks) as compared with their response to pulse modulated MWR. The capability of pulsed MWR to mask acoustic stimuli will also be examined. Calibration of the MWR dose will be in terms of regional absorbed energy density. Recording sites will be suitably marked and verified by histological examination. We will apply these data to the analysis of the biological hazards of pulsed MWR and of the biomedical utility of this interaction of MWR with the central nervous system.